reflection.alu

use std::typing::Type;
use std::builtins::{Struct, Union};

/// Set a field on an struct by name
fn set<T: Struct | Union, F>(obj: &mut T, name: &[u8], value: F) {
    let ty = Type::new::<T>();
    let value_ty = Type::new::<F>();

    let fields = ty.fields();
    for const i in 0usize..fields.len() {
        let field_ty = fields.(i).type();

        if fields.(i).name() == Option::some(name) {
            when field_ty.is_same_as(value_ty) {
                *fields.(i).as_mut_ptr(obj) = value;
                return;
            } else {
                panic!(
                    "expected type {}, got {}",
                    field_ty.debug_name(),
                    value_ty.debug_name()
                );
            }
        }
    }

    panic!("field not found: {}", name);
}

struct Foo {
    bar: i32,
    quux: bool,
}

fn main() {
    let foo: Foo;
    foo.set("bar", 42);
    foo.set("quux", true);

    // These would panic at runtime
    // foo.set("bar", true);
    // foo.set("unknown", 42);

    println!("bar = {}", foo.bar);
    println!("quux = {}", foo.quux);
}